Multiple industries, such as compounding and plastic composite processing, chemical and mineral processing, the food industry, and the pharmaceutical industry, among others, require the conveyance of small particulate matter from one location to another location in order to either incorporate such particles into a product or to remove particulate by-products and waste formed during the manufacturing process. The combustion of coal or similar fuels represents one example of a process that produces small by-product or waste particles (e.g., typically called fly ash) that can be removed from the site of combustion as part of an exhaust gas. The diameter of the small particles that flow in a particle collection or transportation system may range from about several millimeters to about 0.01 micrometers. One feature common to most particle collection or transport systems is that the particles should not be exhausted into the atmosphere because such a release will raise multiple environmental issues and concerns. Thus, various technologies, such as electrostatic precipitators and bag filters, are generally utilized to remove the small particles from the exhaust gas prior to the exhaust gas being released into the atmosphere.
The small particulate matter that will be moved via the transport system typically are collected in one or more hoppers or bins. The transfer of the particles from these bin(s) or hopper(s) to a desired location, such as a compounding vessel or a disposal unit, can be accomplished through the use of a particle collection or transportation system. Such a particle collection or transportation system will generate a pressure differential through the use of compressed air and/or vacuum to cause the small particles to flow from the hopper through a control valve and a conveying line to the desired location. Although this process may seem simple in nature, the movement of small particles can cause significant issues related to the erosive wear of the devices and equipment that are exposed to the flow of these particles.
A particle collection or transportation system is basically a pressure/vacuum line or conveying that is capable of causing a high differential pressure gradient in order to move large quantities of small, relatively abrasive particles. This high differential pressure gradient causes the small particles to flow at high velocities through the narrow gaps present in the control valve, thereby, eroding the valve assembly, reducing the efficiency of the valve, and shortening the effective lifetime expected for the valve. This problem becomes more evident in a valve that is used for the lateral loading of a main pressure/vacuum line. In this case, the lateral-style valve must turn the abrasive particles by an angle of about 90 degrees upon flowing from the hopper into the main pressure/vacuum line.
The abrasive particles can cause the erosion of multiple components within the lateral-style valve, including the body, the gate, and the seat. Such erosion may occur in a relatively short period of time, even on the order of a few weeks. The erosive wear of the valve components ultimately results in a reduced system capacity or excessive down-time to perform repairs, both of which lead to a loss in productivity. Thus, a problem exists in maintaining the efficiency of a valve assembly when it operates in an abrasive environment. Accordingly, there is a continual need for the development of lateral-style valves that exhibit reduced erosive wear and that will provide for high reliability and low maintenance of a system that uses such a valve.